/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_lms_norm_q15.c
*
* Description:	Q15 NLMS filter.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated
*
* Version 0.0.7  2010/06/10
*    Misra-C changes done
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupFilters
 */

/**
 * @addtogroup LMS_NORM
 * @{
 */

/**
* @brief Processing function for Q15 normalized LMS filter.
* @param[in] *S points to an instance of the Q15 normalized LMS filter structure.
* @param[in] *pSrc points to the block of input data.
* @param[in] *pRef points to the block of reference data.
* @param[out] *pOut points to the block of output data.
* @param[out] *pErr points to the block of error data.
* @param[in] blockSize number of samples to process.
* @return none.
*
* <b>Scaling and Overflow Behavior:</b>
* \par
* The function is implemented using a 64-bit internal accumulator.
* Both coefficients and state variables are represented in 1.15 format and
* multiplications yield a 2.30 result. The 2.30 intermediate results are
* accumulated in a 64-bit accumulator in 34.30 format.
* There is no risk of internal overflow with this approach and the full
* precision of intermediate multiplications is preserved. After all additions
* have been performed, the accumulator is truncated to 34.15 format by
* discarding low 15 bits. Lastly, the accumulator is saturated to yield a
* result in 1.15 format.
*
* \par
* 	In this filter, filter coefficients are updated for each sample and the updation of filter cofficients are saturted.
*
 */

void arm_lms_norm_q15(
    arm_lms_norm_instance_q15* S,
    q15_t* pSrc,
    q15_t* pRef,
    q15_t* pOut,
    q15_t* pErr,
    uint32_t blockSize)
{
	q15_t* pState = S->pState;                     /* State pointer */
	q15_t* pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
	q15_t* pStateCurnt;                            /* Points to the current sample of the state */
	q15_t* px, *pb;                                /* Temporary pointers for state and coefficient buffers */
	q15_t mu = S->mu;                              /* Adaptive factor */
	uint32_t numTaps = S->numTaps;                 /* Number of filter coefficients in the filter */
	uint32_t tapCnt, blkCnt;                       /* Loop counters */
	q31_t energy;                                  /* Energy of the input */
	q63_t acc;                                     /* Accumulator */
	q15_t e = 0, d = 0;                            /* error, reference data sample */
	q15_t w = 0, in;                               /* weight factor and state */
	q15_t x0;                                      /* temporary variable to hold input sample */
	//uint32_t shift = (uint32_t) S->postShift + 1u; /* Shift to be applied to the output */
	q15_t errorXmu, oneByEnergy;                   /* Temporary variables to store error and mu product and reciprocal of energy */
	q15_t postShift;                               /* Post shift to be applied to weight after reciprocal calculation */
	q31_t coef;                                    /* Teporary variable for coefficient */
	q31_t acc_l, acc_h;
	int32_t lShift = (15 - (int32_t) S->postShift);       /*  Post shift  */
	int32_t uShift = (32 - lShift);

	energy = S->energy;
	x0 = S->x0;

	/* S->pState points to buffer which contains previous frame (numTaps - 1) samples */
	/* pStateCurnt points to the location where the new input data should be written */
	pStateCurnt = &(S->pState[(numTaps - 1u)]);

	/* Loop over blockSize number of values */
	blkCnt = blockSize;


#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */

	while(blkCnt > 0u) {
		/* Copy the new input sample into the state buffer */
		*pStateCurnt++ = *pSrc;

		/* Initialize pState pointer */
		px = pState;

		/* Initialize coeff pointer */
		pb = (pCoeffs);

		/* Read the sample from input buffer */
		in = *pSrc++;

		/* Update the energy calculation */
		energy -= (((q31_t) x0 * (x0)) >> 15);
		energy += (((q31_t) in * (in)) >> 15);

		/* Set the accumulator to zero */
		acc = 0;

		/* Loop unrolling.  Process 4 taps at a time. */
		tapCnt = numTaps >> 2;

		while(tapCnt > 0u) {

			/* Perform the multiply-accumulate */
#ifndef UNALIGNED_SUPPORT_DISABLE

			acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);
			acc = __SMLALD(*__SIMD32(px)++, (*__SIMD32(pb)++), acc);

#else

			acc += (((q31_t) * px++ * (*pb++)));
			acc += (((q31_t) * px++ * (*pb++)));
			acc += (((q31_t) * px++ * (*pb++)));
			acc += (((q31_t) * px++ * (*pb++)));

#endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/

			/* Decrement the loop counter */
			tapCnt--;
		}

		/* If the filter length is not a multiple of 4, compute the remaining filter taps */
		tapCnt = numTaps % 0x4u;

		while(tapCnt > 0u) {
			/* Perform the multiply-accumulate */
			acc += (((q31_t) * px++ * (*pb++)));

			/* Decrement the loop counter */
			tapCnt--;
		}

		/* Calc lower part of acc */
		acc_l = acc & 0xffffffff;

		/* Calc upper part of acc */
		acc_h = (acc >> 32) & 0xffffffff;

		/* Apply shift for lower part of acc and upper part of acc */
		acc = (uint32_t) acc_l >> lShift | acc_h << uShift;

		/* Converting the result to 1.15 format and saturate the output */
		acc = __SSAT(acc, 16u);

		/* Store the result from accumulator into the destination buffer. */
		*pOut++ = (q15_t) acc;

		/* Compute and store error */
		d = *pRef++;
		e = d - (q15_t) acc;
		*pErr++ = e;

		/* Calculation of 1/energy */
		postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
		                          &oneByEnergy, S->recipTable);

		/* Calculation of e * mu value */
		errorXmu = (q15_t)(((q31_t) e * mu) >> 15);

		/* Calculation of (e * mu) * (1/energy) value */
		acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));

		/* Weighting factor for the normalized version */
		w = (q15_t) __SSAT((q31_t) acc, 16);

		/* Initialize pState pointer */
		px = pState;

		/* Initialize coeff pointer */
		pb = (pCoeffs);

		/* Loop unrolling.  Process 4 taps at a time. */
		tapCnt = numTaps >> 2;

		/* Update filter coefficients */
		while(tapCnt > 0u) {
			coef = *pb + (((q31_t) w * (*px++)) >> 15);
			*pb++ = (q15_t) __SSAT((coef), 16);
			coef = *pb + (((q31_t) w * (*px++)) >> 15);
			*pb++ = (q15_t) __SSAT((coef), 16);
			coef = *pb + (((q31_t) w * (*px++)) >> 15);
			*pb++ = (q15_t) __SSAT((coef), 16);
			coef = *pb + (((q31_t) w * (*px++)) >> 15);
			*pb++ = (q15_t) __SSAT((coef), 16);

			/* Decrement the loop counter */
			tapCnt--;
		}

		/* If the filter length is not a multiple of 4, compute the remaining filter taps */
		tapCnt = numTaps % 0x4u;

		while(tapCnt > 0u) {
			/* Perform the multiply-accumulate */
			coef = *pb + (((q31_t) w * (*px++)) >> 15);
			*pb++ = (q15_t) __SSAT((coef), 16);

			/* Decrement the loop counter */
			tapCnt--;
		}

		/* Read the sample from state buffer */
		x0 = *pState;

		/* Advance state pointer by 1 for the next sample */
		pState = pState + 1u;

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* Save energy and x0 values for the next frame */
	S->energy = (q15_t) energy;
	S->x0 = x0;

	/* Processing is complete. Now copy the last numTaps - 1 samples to the
	   satrt of the state buffer. This prepares the state buffer for the
	   next function call. */

	/* Points to the start of the pState buffer */
	pStateCurnt = S->pState;

	/* Calculation of count for copying integer writes */
	tapCnt = (numTaps - 1u) >> 2;

	while(tapCnt > 0u) {

#ifndef UNALIGNED_SUPPORT_DISABLE

		*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
		*__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;

#else

		*pStateCurnt++ = *pState++;
		*pStateCurnt++ = *pState++;
		*pStateCurnt++ = *pState++;
		*pStateCurnt++ = *pState++;

#endif

		tapCnt--;

	}

	/* Calculation of count for remaining q15_t data */
	tapCnt = (numTaps - 1u) % 0x4u;

	/* copy data */
	while(tapCnt > 0u) {
		*pStateCurnt++ = *pState++;

		/* Decrement the loop counter */
		tapCnt--;
	}

#else

	/* Run the below code for Cortex-M0 */

	while(blkCnt > 0u) {
		/* Copy the new input sample into the state buffer */
		*pStateCurnt++ = *pSrc;

		/* Initialize pState pointer */
		px = pState;

		/* Initialize pCoeffs pointer */
		pb = pCoeffs;

		/* Read the sample from input buffer */
		in = *pSrc++;

		/* Update the energy calculation */
		energy -= (((q31_t) x0 * (x0)) >> 15);
		energy += (((q31_t) in * (in)) >> 15);

		/* Set the accumulator to zero */
		acc = 0;

		/* Loop over numTaps number of values */
		tapCnt = numTaps;

		while(tapCnt > 0u) {
			/* Perform the multiply-accumulate */
			acc += (((q31_t) * px++ * (*pb++)));

			/* Decrement the loop counter */
			tapCnt--;
		}

		/* Calc lower part of acc */
		acc_l = acc & 0xffffffff;

		/* Calc upper part of acc */
		acc_h = (acc >> 32) & 0xffffffff;

		/* Apply shift for lower part of acc and upper part of acc */
		acc = (uint32_t) acc_l >> lShift | acc_h << uShift;

		/* Converting the result to 1.15 format and saturate the output */
		acc = __SSAT(acc, 16u);

		/* Converting the result to 1.15 format */
		//acc = __SSAT((acc >> (16u - shift)), 16u);

		/* Store the result from accumulator into the destination buffer. */
		*pOut++ = (q15_t) acc;

		/* Compute and store error */
		d = *pRef++;
		e = d - (q15_t) acc;
		*pErr++ = e;

		/* Calculation of 1/energy */
		postShift = arm_recip_q15((q15_t) energy + DELTA_Q15,
		                          &oneByEnergy, S->recipTable);

		/* Calculation of e * mu value */
		errorXmu = (q15_t)(((q31_t) e * mu) >> 15);

		/* Calculation of (e * mu) * (1/energy) value */
		acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));

		/* Weighting factor for the normalized version */
		w = (q15_t) __SSAT((q31_t) acc, 16);

		/* Initialize pState pointer */
		px = pState;

		/* Initialize coeff pointer */
		pb = (pCoeffs);

		/* Loop over numTaps number of values */
		tapCnt = numTaps;

		while(tapCnt > 0u) {
			/* Perform the multiply-accumulate */
			coef = *pb + (((q31_t) w * (*px++)) >> 15);
			*pb++ = (q15_t) __SSAT((coef), 16);

			/* Decrement the loop counter */
			tapCnt--;
		}

		/* Read the sample from state buffer */
		x0 = *pState;

		/* Advance state pointer by 1 for the next sample */
		pState = pState + 1u;

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* Save energy and x0 values for the next frame */
	S->energy = (q15_t) energy;
	S->x0 = x0;

	/* Processing is complete. Now copy the last numTaps - 1 samples to the
	   satrt of the state buffer. This prepares the state buffer for the
	   next function call. */

	/* Points to the start of the pState buffer */
	pStateCurnt = S->pState;

	/* copy (numTaps - 1u) data */
	tapCnt = (numTaps - 1u);

	/* copy data */
	while(tapCnt > 0u) {
		*pStateCurnt++ = *pState++;

		/* Decrement the loop counter */
		tapCnt--;
	}

#endif /*   #ifndef ARM_MATH_CM0 */

}


/**
   * @} end of LMS_NORM group
   */
